Arc welding of studs



E. DASH Dec, 20, 1949 ABC WELDING OF STUDS Filed Nov. 12, 1948 INVENTOR.EQWARD DASH BY ATTORNEY Patented Dec. 20, 1949 UNITED STATES PATENTGFFICE 9 Claims.

amended April 30, 1928; 370 0. G. 757) This invention relates to studwelding, and more particularly to the art of arc welding an aluminumstud to an aluminum member, such as a plate or bulkhead.

It is an object of this invention to provide a method and apparatus foreffectuating stronger and more uniform stud welds to aluminum members.

It is another object of this invention to provide a method and apparatuswhereby an aluminum stud may be are welded to an aluminum member in anyposition; that it, the welding operation may be effected with the studpointing up, down, horizontally, or at any intermediate angle betweenthese positions.

The arc welding method of this invention is characterized by acombination of two features: (1) the use of an aluminum stud juxtaposedadjacent an aluminum member, (2) surrounded at its juxtaposed end by aninert gas during the welding operation. More specifically, the inventionis characterized by the use, with an inert gas, of a particular type ofaluminum stud, namely, a stud having from 4.5 per cent to 6.0 per centsilicon.

Also in accordance with the instant invention, there is provided auseful apparatus for practicing the method aspect of the invention, thisapparatus being a sleeve adapted to be fitted to the end of a weldinggun and surrounding the stud. The sleeve has a nipple in the wallthereof through which a stream of inert gas may be constantly admittedto the weld region during the welding operation.

Other objects and many of the attendant advantages of the invention willbe readily appreciated as the same become better understood by r ferenceto the following description when considered in connection with theaccompanying drawings, wherein:

Fig. l is an elevation, partially sectioned, of a stud welding gunholding a stud to be welded to a plate, the gun having mounted thereonthe sleeve of the instant invention, which allows gas to be ejected intothe region surrounding the welding operation; and

Figs. 2, 3 and 4 are fragmentary detailed views, partially sectioned,showing certain steps in the method constituting the instant invention.

In Fig. l, H designates a stud welding gun including a slidably mountedmagnetic plunger l2, which reciprocates within a solenoid 33 in thebarrel of the gun, being biased outwardly thereof by a helical spring l3at the rear of the gun. The reciprocable plunger 12 extends from themuzzle of the stud gun and is axially bored at the end as shown at [4,to form a chuck for the reception of a stud l6, adapted to be welded toan aluminum member such as plate ii. The chuck end of the plunger i2 isalso slotted as shown at l5 to lend added resiliency to the gripping ofthe stud Hi.

In practicing the instant invention, the stud i5 is made primarily ofaluminum and contains from 4.5 per cent to 6.0 per cent silicon.

More specifically, the stud l6 has the following general composition:

Per cent Silicon 4.5 to 6.0 Iron not over 0.8 Copper not over 0.4Manganese not over 0.3 Zinc not over 0.2 Titanium not over 0.2 Magnesiumnot over 0.05 Total other impurities not over 03 Aluminum remainderMounted around the chuck end of the plunger i2 is a helical sprin 28,which abuts a nut 19 secured to the plunger l2, and forming a shoulderfor the spring. The spring i8 extends somewhat beyond the chuck end ofthe plunger l2 so as to partially surround the stud l6. Secured as byspot welding or other suitable method to the extended end of the springis a sleeve 25, through which the stud it extends. The sleeve 25 ispreferably made of metal and has fitted into the end thereof a porcelainor other ceramic ferrule 22, which is adapted to abut the plate 5'?during the welding operation. Secured to the wall or the sleeve 2i is anipple 23, by means of which an inert gas may be admitted to the regionsurrounding the end of the stud Iii during the welding operation.

The nipple is connected to a source of inert gas, such as tank 2t,through flexible tubing 26, this gas conduit including an on-off valve21, which is preferably electrically controlled from a control source20. A preferred gas is helium, although any suitable inert gas may beused.

The stud I5 is preferably formed with a somewhat hemispherical head 29,although it is to be understood that any form of stud may be used in thepractice of the instant invention.

The invention is adapted for arc welding an aluminum stud to anysuitable member, such as plate ll, the member preferably beingsubstantially of aluminum, or having at least '75 per cent aluminum inits composition.

The operation of the instant invention will now be described withparticular reference to Figs. 2, 3 and 4:. The operator first inserts astud iii through the sleeve 2| and into the bore l4 in the chuck end ofthe plunger l2, where it is firmly held by frictional engagement. Hethen presses the gun and stud against the plate ll, as shown in Fig. 2,until the stop rods 3|, mounted on the gun parallel to the plunger l2,abuts the plate ll. When the trigger 32 of the welding gun is actuated,the following described steps take place automatically, being controlledby means of the electric controller shown schematically at 23. First,the valve 21 is opened automatically to admit a stream of helium fromthe tank EA to the interior of the sleeve 2|, from which it passes outthe extended end upon the plate [1. This drives air from that region andsurrounds the abutting areas between stud it and plate H with a mediumwhich is chemically inert.

Next in the automatic sequence of steps, the solenoid 33 is energized,pulling the plunger I2 backward into the body of the gun 5! against theforce of the spring [3 to the position indicated in Fig. 3.Simultaneously, the welding current is initiated: from the energizingsource, to the gun I l, to the chuck end of the plunger l2, thence tothe stud IE, across the arcing area 34-, to the plate H, from whence itreturns to the energizing source. The are formed at 3:1 is maintainedautomatically for the necessary time in the inert atmosphere, followingwhich solenoid 33 is automatically de-energized and the spring I3 forcesthe stud [6 against the plate H. Simultaneously, the welding current isstopped. The hemispherical head 29 and the adjacent region of the platell, having been well-plasticized by the heat of the are current, thestud I6 is readily forced against the plate ii and integrated therewith,as shown in Fig. i, by the pushing action of the spring It. The ultimateconfiguration of the completed Weld 36 is determined in part by theceramic ferrule 22, which serves as a partial mold therefor by limitingoutward spreading of the plasticized material. Immediately following theshutting off of the weld current and the de-energization of the solenoid33, the valve 2'! is automatically closed to complete a welding cycle.

The operator then withdraws the gun away from the plate ll, the stud l6slipping from the bore l4 and remaining in place, welded to the plate11. The gun is then ready for the reception of another stud Hi, and arepetition of the stud welding operation at any other desired point onthe plate ll.

Use of the particular stud described hereinbefore in the environment ofan inert gas for arc welding has been found to produce welds of superiorphysical properties, such as tensile strength, ductility, fatiguestrength, and impact strength, over stud welds not employing thisparticular combination. The method of the instant invention also has theadvantage of being usable in any attitude of the welding gun; the gunmay be pointed up, down, horizontally, or at any intermediate anglebetween these positions, with equally efiicacious results.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. t is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

The invention described herein may be manu- 1 factured and used by orfor the Government of the United States of America for governmentalpurposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. The method of automatically end welding a stud to a member whichcomprises juxtaposing the head end of a hemispherically headed studadjacent the member, forming a welding are between the stud and themember, surrounding the juxtaposed areas with an inert gas, said memberbeing composed of at least per cent aluminum, said stud having thefollowing general composition:

Per cent Silicon 4.5 to 6.0 Iron not over 0.8 Copper not over 0.4Manganese anot over 0.3 Zinc not over 0.2

Titanium not over 0.2 Magnesium not over 0.05 Total other impurities notover 0.3 Aiuminum remainder and pressing said stud and member togetherto consummate the weld.

2. The method of automatically end welding a stud to a member whichcomprises juxtaposing the end of a stud adjacent the member, forming aWelding are between the stud and the member, surrounding the juxtaposedareas with an inert gas, said member being composed of at least 75 percent aluminum, said stud having the following general composition:

Per cent Silicon 4.5 to 6.0 Iron not over 0.8 Copper not over 0.4Manganese not over 0.3 Zinc not over 0.2 Titanium not over 0.2 Magnesiumnot over 0.05 Total other impurities not over 0.3 Aluminum remainder andpressing said stud and member together to consummate the weld.

3. The method or automatically end welding a stud to a member whichcomprises juxtaposing the end of a stud adjacent the member, passing awelding current thru the stud and member to form an arc therebetween,filling the arc region with an inert gas, and pressing said stud andmember together to consummate the weld, said stud being composedprimarily of aluminum and containing between 4.5 percent and 6.0 percentsilicon, and said member being composed of at least '75 percentaluminum.

4.. In combination with a welding gun adapted to receive a stud to bewelded to a member: a helical spring fitted securely over the end of thegun which receives the stud, a metal sleeve secured coaxially to theother end of said spring, a ceramic ferrule fitted to the extended endof said sleeve to abut against the member and to prevent shortcircuiting between the sleeve and the member. and a nipple in the wallof said sleeve for admitting gas to the region surrounding the end ofthe stud.

5. In combination with a welding gun adapted to receive a stud to bewelded to a member: a helical spring fitted securely over the end of thegun which receives the stud, a sleeve secured coaxially to the other endof said spring, the extended end of said sleeve being of ceramicmaterial whereby it may be abutted against the member to prevent shortcircuiting between the stud and the member, and a nipple in the wall ofsaid sleeve for admitting gas to the region surrounding the end of thestud.

6. In combination with a welding gun adapted to receive a stud to bewelded to a member: a helical spring fitted securely over the end of thegun which receives the stud, a sleeve secured coaxially to the other endof said spring, and a nipple in the wall of said sleeve for admittinggas to the region surrounding the end of the stud.

'7. A device for use in surrounding a stud welding operation with inertgas, comprising a metal sleeve adapted to be fitted around a stud heldin a welding gun, a ceramic ferrule fitted to said sleeve at the endthereof, adapted to abut a member to which the stud is to be welded, anda nipple in the wall of said sleeve through which gas may be admitted tothe region around the end of the stud.

8. A device for use in surrounding a stud welding operation with inertgas, comprising a sleeve adapted to be fitted around a stud held in awelding gun, the end of said sleeve being of ceramic material andthereby adapted to abut a member to which the stud is to be welded, anda nipple in the wall of said sleeve through which gas may be admitted tothe region around the end of the stud.

9. A device for use in surrounding a stud welding operation with inertgas, comprising a sleeve adapted to be fitted around a stud held in awelding gun, and a nipple in the wall of said sleeve through which gasmay be admitted to the region around the end of the stud.

EDWARD DASH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,716,614 Bergman a- June 11,1929 1,746,081 Hobart Feb. 4, 1930 2,315,502 Crecca et a1. Apr. 6, 19432,413,189 Nelson Dec. 24, 1946

